UPC EETAC Bachelor's Degree in Telecommunications Systems and in Network Engineering EEL

L1.4

Lecture 5

L1.5: Designing circuits using only-NOR and only-NAND

P1 design plan A: designing circuits using only one kind of gates

L1.6

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1.5.2.1.3. Only-NOR gates

1.5.2.1.4. Only-NAND gates

These are two techniques based on simply rearranging the equations for implementing circuits using only one type of logic gate: NAND or NOR. Fifty years ago, it meant being able to implement any combinational application using only one classic chip, such as 74LS00 (quad NAND2, LS-TTL) or CD4001B (Quad NOR2, CMOS).

Universal gates

Fig. 1. a) Classic chip 74LS00 (quad NAND2, LS-TTL). b) Chip CD4001B (Quad NOR2, CMOS).

We can add easily these new circuits to our concept map, as any equation can be tranformed for only-NAND or only-NOR implementations:

Fig. 2. Examples of circuits designed from the initial specifications (truth table). Equations can be modified to invent circuits using only one type of gate: NOR or NAND.

Now that you know how to use the minimiser minilog, what is left to finish discussion on P1 design plans is to examine how to build circuits from the same truth table using only-NAND (Circuit_5, Circuit_7, Circuit_10) or only-NOR gates (Circuit_6, Circuit_8). 

Discussion only NAND, only NOR
Discussion on how to use only NAND and only NOR

Fig. 3. Class discussion on how to create Circuit_W5 from Circuit_W3. Step1: learn to build any gate using only-NOR or only-NAND. Step 2: learn how to convert a complete equation. Step 3: complete your classnotes and apply these concepts to create other circuits, for instance: how to build Circuit_W11 from Circuit_W3 using only 2-input NOR gates? how to build Circuit_W12 from Circuit_W8 using only 2-input NOR gates?

Study also these notes: circuits using only NAND or only NOR gates. This is a trick to use only-NOR2 or only-NAND2 rec.

This Circuit_K3 is another complete design example.

1.5.2.1.5. Any kind of nonstandard equation.

Thus, at this point you see how the many example circuits presented in P1 are conceived mixing any combination of logic equations. CSD course is totally based on examples and tutorials the link to which is always below specifications of highlighted projects.

other circuit tutorials and assignments

Exercise: Design the Circuit_W using only NAND of 2-inputs (NAND2). Check it using Proteus (CMOS chips, or LS-TTL chips).

Circuit_W using NAND2

Remember: (1) Specifications; (2) Plan in several steps; (3) Develop; (4) Test.